It is common to incorporate data objects into a document file. For example, Microsoft Word™ allows a user to include Microsoft Visio™ diagram objects into a document file, which allows the user to not only view the diagram objects as they appear in the document file, but also to invoke a Microsoft Visio™ editing environment to edit the diagram objects. Such an approach, however, has several shortcomings. For example, by storing the entirety of the data objects as part of the document file, the file size becomes very large, and the document file becomes less portable as more data objects are incorporated in the file. Also, if the document file is to be shared with other users, each having different access privileges to different data within the stored data object, it is difficult to set differentiating access policies for various data of the stored data objects in a single document file.